• 1¼ cups flour
• 2½ teaspoons baking powder
• Pinch salt
• 5 large eggs, separated
• 1¼ cups sugar
• 5 tablespoons boiling water
• 1 teaspoon vanilla extract

An 1½- by 17½-inch jelly roll pan, or a sheet pan with 1-inch sides

Preheat the oven to 350 degrees.

Line the bottom of a jelly roll pan with parchment paper.

Sift together the flour, baking powder, and salt. Set aside.

Put the egg yolks and sugar in the bowl of an electric mixer. Using the whisk attachment, whip on high speed until thick and pale yellow. Reduce to medium speed and slowly add the water and the vanilla. Scrape the sides and bottom of the bowl. Return to high speed and continue whipping for about 5 minutes, until mixture is again thick and ribbony.

Fold the dry ingredients into the egg-sugar mixture.

Put the egg whites in a separate bowl of an electric mixer. With the clean whisk attachment, whip on high speed until soft peaks form. Fold half of the whipped whites into the batter and then fold in the remaining whites. Spread the batter evenly into the pan.

Bake the cake for about 15 minutes, until it is golden brown and springs back when lightly touched.